The present invention relates to radio frequency shielding and, more particularly, to a radio frequency shield door system for blocking radio frequency electromagnetic radiation through a doorway to a livable space or shield room.
Electromagnetic shielding is the practice of reducing the electromagnetic field in a space or enclosure by blocking the field with barriers made of conductive or magnetic materials. Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF shielding. The amount of reduction depends very much upon the material used (typically sheet metal or metal screens), its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in the shield to an incident electromagnetic field. Any holes in the shield or mesh must be significantly smaller than the wavelength of the radiation that is being kept out, or the enclosure will not effectively reduce the radio frequency electromagnetic radiation.
This necessity for minimizing holes, apertures and gaps between the RF shielding door and the doorway, has resulted in complicated sealing mechanisms and RF shield doors to date that are notoriously difficult to open and close. For example, typical spring finger contact mechanisms used in current RF shielded doors create a large amount of resistance in opening and closing the door as the springs exert a lateral force on a knife edge or sealing surface of a door which requires a great amount of energy to overcome. This in turn requires the use of large handles, cam blocks, pivot points, rollers, linkages, and other wear items to overcome/exert the necessary force to open and close the door. As a corollary, these complicated mechanisms have many potential failure points, wherein failures can render the door inoperable. This poses a safety concern since personnel may become trapped in a shield room.
Alternative methods for sealing off a doorway include complicated mechanisms such as air bladders or pneumatically assisted door latches. These solutions require frequent maintenance and repairs, and their complications also invite failure.
As can be seen, there is a need for a radio frequency shield door system for complete and effective RF and electromagnetic shielding through a doorway to a livable space or shield room by providing an RF door seal which takes minimal force to open and close.